D. H. Crandall

Measurement of the contribution of excitation autoionization to electron-impact ionization of ions: Ti3+, Zr3+, Hf3+, and Ta3+

Measurements were made of the cross section for electron-impact single ionization of the transition-element ions Ti/sup 3 +/, Zr/sup 3 +/, Hf/sup 3 +/, and Ta/sup 3 +/ for an electron-energy range from threshold to 1000 eV. The cross sections are enhanced by as much as a factor of 20 due to excitation-autoionization primarily involving ..delta..n = 0 transitions, np/sup 6/nd/sup m/..-->..np/sup 5/nd/sup m+1/. Comparisons with recent theoretical predictions show reasonable agreement between measured and predicted positions of the autoionization states; however, the magnitudes of the theoretical cross sections are greater than the experimental values by a factor of approximately 2.5.

System for Data Acquisition from High Voltage Terminals

An inexpensive data acquisition system has been designed to provide high voltage isolation for data acquisition in analog, digital, and pulse modes. The telemetry system uses GaAs light sources, fiber optics, and phototransistors to accomplish the data transmission. Prewired logic boards have been adapted to accomplish the timing and logic functions. Seven decades of digital data are transmitted error free, pulse data can be transmitted at rates up to 1 MHz, and analog data are transmitted with 0.05% full scale accuracy.

Survey of experimental and theoretical electron-impact ionization cross sections for transition metal ions in low stages of ionization

Electron-ion crossed beams measurements and distorted-wave theory have been employed to make a study of electron-impact ionization for transition metal ions in low stages of ionization. The atomic ions Ti+, Ti/sup 2/+, Ti/sup 3/+, Fe+, Fe/sup 2/+, Fe/sup 3/+, Fe/sup 4/+, Ni+, Ni/sup 2/+, Ni/sup 3/+, Cu+, Cu/sup 2/+, and Cu/sup 3/+ are examined.

Electron impact ionization of multicharged ions at ORNL: 1980-1984

Absolute cross sections are presented in graphs and tables for single ionization of forty-one ions, multiple ionization of four ions, and for dissociation and ionization of two molecular ions by electron impact. This memo is the third in a series of manuscripts summarizing previously published as well as unpublished ionization cross section measurements at ORNL; contents of the two previous memos are also referenced in this work. All work tabulated in this memo involved ion beams generated in the ORNL-ECR ion source and utilized the ORNL electron-ion crossed beams apparatus. Target ions range from atomic number Z = 8 (oxygen) to Z = 92 (uranium) in initial charge states from +1 to +16. Electron impact energies typically range from threshold to 1500 eV.